TRIPOLI, Libya — Evidence emerged Friday that Col. Moammar Gaddafi’s retreating forces executed scores or even hundreds of political prisoners this week, even as victorious rebel fighters appear to have carried out their own abuses.

Survivors of an attack by pro-Gaddafi troops said they had watched as fellow prisoners were mowed down by machine-gun fire, minutes after being told they were free.

But Gaddafi loyalists were also targets of apparent extrajudicial killings. Those deaths have cast a dark shadow over Libya’s newfound freedom and call into question whether the rebels will break with Gaddafi’s blood-soaked style of governance or merely mimic it.

“In Tripoli, we are seeing the same pattern in recent days that we saw earlier in the east,” said Diana Eltahawy, Libya researcher for Amnesty International. She described a record of abuse, torture and the extrajudicial killing of captured pro-Gaddafi fighters that has followed the rebels from east to west as they have taken over the country.

In the wreckage of a Tripoli fire station and field hospital on Friday, five fighters loyal to Gaddafi lay in agony and blood, apparently left to die by their vanquishers. They had been without food, water or medical attention for two days.

Rebel fighters patrolling the compound knew the men were there, but scarcely seemed to care. “We would take them to the hospital, but there are no hospitals,” said Salah Mansoor, a law school graduate and shopkeeper dressed in a Liverpool soccer shirt. “There are no cars to take them,” he added, as a taxi cruised by.

A few minutes’ drive from the fire station, at least 15 bodies, most of them Gaddafi’s black African supporters, lay rotting in the sun at a traffic junction outside his Bab al-Aziziyah complex. Several of the dead wore green pieces of cloth wrapped around their wrists to signal loyalty to the Gaddafi regime.

The men may have died during Tuesday’s battle for Bab al-Aziziyah, and several were wearing military fatigues. But not all of them looked like ordinary battlefield deaths. Two dead men lay face down on the grass, their hands bound behind their backs with plastic cuffs.

The worst treatment of Gaddafi loyalists appeared to be reserved for anyone with black skin, whether they hailed from southern Libya or from other African countries. Darker-skinned prisoners were not getting the same level of medical care in a hospital in rebel-held Zawiyah as lighter-skinned Arab Libyans, Eltahawy said.

Rebels say Gaddafi employed gunmen from sub-Saharan Africa to shore up his army against his own people, and those fighters have elicited intense enmity from Libyans. But many of the detainees in Zawiyah told Amnesty International they were merely migrant workers “taken at gunpoint from their homes, workplaces and the street on account of their skin color,” Eltahawy said.

The civilian leaders of the anti-Gaddafi uprising have publicly condemned reprisals against loyalist troops. But the officials are in the eastern city of Benghazi, far from the most intense fighting in recent weeks, which has been focused in western Libyan. Even in the east, the civilian leadership appears to have had little success in preventing fighters from carrying out revenge attacks.

The reprisals could become a powerful element in persuading Gaddafi loyalists in the holdout city of Sirte to fight to the death, said Shashank Joshi of the Royal United Services Institute, a London-based think tank.

While the rebels’ Transitional National Council has projected an image of reconciliation, confirmation of extrajudicial killings would be “an absolute nightmare for the rebels,” he said.

Executions by loyalists

The abuses have hardly been limited to the rebel side. Gaddafi’s troops apparently executed more than 100 political prisoners in two separate incidents before they fled, according to survivors.

Trader Abdel-ati Bin Halim, 42, said he had been arrested at a checkpoint in the coastal city of Zintan two weeks ago, taken into custody after his car alarm went off and soldiers accused him of signaling to NATO with the flashing lights.

After being bound, gagged and beaten, he was kept for a week with up to 200 other people, packed in a hanger at the Yarmouk military base in Tripoli, with only enough water for the oldest people to wet their lips. Then, as the balance of power in the capital started shifting toward the rebels, the guards said they were leaving the door open.

“ ‘Wait half an hour,’ then leave,’ they told us,” Bin Halim said. But when the prisoners pushed open the doors, they were greeted with a hail of machine-gun fire. As bodies piled up on the floor, Bin Halim took refuge behind some tires before making a run for safety with several others.

Escaping with bullet wounds to his knee and elbow, he eventually arrived at a hospital in central Tripoli. “I can’t believe I made it,” he said from his hospital bed.

Eltahawy said Amnesty had received “very strong testimony” to back up Bin Halim’s account. She said she believed at least 23 people had escaped out of a total of 150 or 160 captives from the incident he described, with four in the hospital.

At another hospital in Tripoli, doctors said they had received 17 bodies of people they believed were executed by their guards inside Bab al-Aziziyah as rebels advanced, in a similar but separate incident.

Hunting for Gaddafi

On Friday, rebels fought isolated pockets of resistance as Libyan special forces hunted for Gaddafi and his sons after clearing one of his loyalists’ last major strongholds in the capital.

The streets of Tripoli were largely deserted except for rebel fighters manning checkpoints. Rebels seemed to have control of most of the Abu Salim neighborhood, where they had routed Gaddafi loyalists the previous day. Black smoke billowed from the main market, and broken branches, glass, trash and bullets were strewn over the streets between shot-up cars and checkpoints.

Abdul Majid Mgleta, a rebel commander, said he expected the rebels to mop up the last remaining pockets of resistance in Tripoli within 72 hours, and said he hoped to capture Gaddafi in a similar time frame. “We have information from our own intelligence,” he told reporters in the capital.

In eastern Libya, rebel fighters remained stalled Friday outside the coastal oil terminal of Ras Lanuf, which was coming under rocket fire from pro-Gaddafi forces based in his home town and tribal power base of Sirte, about 130 miles to the west.

Overnight Thursday, NATO struck a surface-to-air missile launcher, 29 military vehicles and a major command post in and around Sirte, NATO officials said. They said they could not confirm ongoing operations on Friday for security reasons.

Correspondents Thomas Erdbrink in Tripoli and Leila Fadel in Benghazi contributed to this report.